MXPA98003365A

MXPA98003365A - Floating transceiver assignment for cellular radio.

Info

Publication number: MXPA98003365A
Application number: MXPA98003365A
Authority: MX
Inventors: Ward Christopher
Original assignee: Nortel Networks Ltd
Priority date: 1997-05-02
Filing date: 1998-04-29
Publication date: 2002-03-14
Also published as: CA2236515C; EP0876074A1; CA2236515A1; BR9801538A; US6104930A

Abstract

A frequency allocation method for allocating carrier frequencies to a plurality of fixed beams in a cellular radio based transceiver station comprises maintaining a reserve pool of carrier frequencies (100), such that any available carrier frequency can be allocated to any fixed beam at any one time in order to deal with capacity demands from mobile stations within an area covered by a fixed beam (1002). A frequency allocation algorithm operates such as to allow a plurality of transceivers to float anywhere across a plurality of fixed directional beams. More carrier frequencies can be added to a beam to deal with increased mobile station capacity demand. The occupancy of channels on the carrier frequencies is continuously monitored, and the number of carrier frequencies per beam is continuously monitored (1001, 1003), with the object of releasing unused carrier frequencies to a reserve pool of carrier frequencies (1005), allowing redeployment of unused carrier frequencies to other bea ms where necessary (1004). Carrier frequencies are periodically "groomed" by assessing the number of vacant channels on the carrier, and reallocating any un-utilized vacant channels to other carrier frequencies. The grooming process can be constrained to operate during natural gaps in speech, to avoid channel degradation.

Description

ALLOCATION OF FLOATING TRANSCEIVER FOR CELLULAR RADIO FIELD OF THE INVENTION This invention relates to the field of cellular radiocommunication systems and, particularly, to a method and apparatus for the distribution or assignment of carrier frequencies in a plurality of beams.

BACKGROUND OF THE INVENTION Cellular radio systems are currently widely used throughout the world providing telecommunication to mobile users. The frequency bands available for mobile communications are divided into several carrier frequencies. In order to satisfy the demand for transmission capacity within the allocation or distribution of the available frequency band, cellular radio systems divide the geographical area that will be covered in a plurality of cellular areas. Each cell is provided with a base station with which a plurality of mobile stations are communicated within the cell. In general, one object of the design of the cellular radiocommunication system is to have as few base stations as possible, because the base stations are expensive and, it takes a great effort to obtain the P1093 / 98 MX • project permit and, in some areas, adequate cycles for the base station may not be available. In order to have as few base stations as possible, each base station ideally has as large a capacity as possible to service or service as many mobile stations as possible. However, there are fundamental limits on the maximum capacity of users of a base station to service or service mobile stations because the The number of mobile stations that can be served by a base station depends on the available number of carrier frequencies and, these carrier frequencies are a limited resource in a frequency spectrum. In order to physically separate the radiations in them 15 frequencies or at almost equal frequencies, it is known to use directional antennas that produce directional radiation beams in the downlink (from the base station to the mobile communication). The use of directional radiation beams allows for greater reuse of 20 carrier frequencies and, increases the capacity of the system compared to omnidirectional antennas. The type of antenna used in the location or site of the base station can potentially make significant improvements in the capacity of a radio system 25 cellular. The conventional approach is to use antennas P1093 / 98 MX * * omnidirectional, antennas of three sectors of wide directionality or antennas of six sectors. The use of directional antennas in ordinary cellular radio systems is based on the principle of sectorization, as illustrated in Figure 1, in which an area covered by a cellular pattern in which a plurality of cells is shown schematically is shown. nominally hexagonal, in a hexagonal pattern with cluster size N = 7, are each divided between sectors, each extending in a range or interval of 120 ° azimuth. The main source of interference comes from the mobile stations in the so-called first row of reuse cells 100-105, which in the example of Figure 1 are separated from a central cell 106 at a distance of at least two intermediate cells, for example, the cells 107, 108. When using omnidirectional antennas, the base station antenna in the central cell 106 receives interference from the mobile stations of all the first six layers of reuse cells 100-105. However, if the antenna has a nominal beam width of 120 ° corresponding to a sectorized cell in three sectors (a three-sector or trisectorized configuration) the interference is received from the mobile stations only in the first two cells of the cell.

P1093 / 98 MX reuse 100, 101. The situation can be improved using an antenna with a beam width of 60 °, corresponding to a configuration of six sectors, in which case, the interference is received from the mobiles in only one of the first row of cells. One approach suggested previously to increase system capacity by increasing frequency reuse is that of an antenna pattern of the base station comprising beams of narrow angular or express widths in both azimuth and elevation, as shown in the Figures 2 and 3 of the present. The prior art literature recognizes many of the potential benefits of narrow or narrow beam antennas. See "A Spectrum Efficient Cellular Base Station Antenna Architecture", SCS ales and MA Beach, Personal and Mobile Radio Communications Conference, Arwick, United Kingdow 1991, and "Proposed Advanced Base Station Antennas form Future Cellular Mobile Radio Systems", S Davies, RJ Long and E. Vinnal, Australian Telecoms Research, Vol. 22, No. 1 pp. 53-60. Although a narrow or narrow radiation beam is formed at radio frequencies normally in the 900 MHz, 1800 MHz or 1900 MHz bands, A narrow or narrow beam can be viewed in a useful way as analogous to looking for light beams emanating from the base station and tracking or tracking the mobiles. When they are contrasted with P1093 / 98 MX an antenna of three sectors or trisectorizadas or inidireccional, these creates a trajectory of transmission of high quality with minimum interference. A plurality of said narrow beams is provided in each sector of 120 °. A narrow radiation beam 200 can be directed by an intelligent antenna 201 of the base station to a desired mobile station 102 and, tracks or tracks the movements of the mobile. When compared to a multidirectional antenna, this narrow or narrow beam has the double benefit of having a high gain, leading or leading to an increase in range in a limited thermal noise environment, and rejecting the interference of cells using the reuse of co-frequency, due to the spatial separation of beams, thus allowing a greater capacity in a cell without division of the cell. An increase in capacity is obtained through a more restricted reuse of frequency through the network. For the purposes of this document, the use of the word "omnidirectional" is intended to include the meaning of having radiation coverage over an area that corresponds substantially to the entire geographic area of a cell. When each cell has several narrow intelligent antennas that have narrow beams which track individual mobiles, a reduction in P1093 / 9S MX the global ratio of carrier to interference (C / I), due to the statistical probability that different beams are reused the same carrier frequency will be pointing in different directions, have different azimuth and different elevations. The random locations of the mobiles (and hence the direction of the beam) means that there is a low probability of intersecting the interference and, the probability of two or more beams of the same carrier frequency intersecting each other decreases. The narrower or narrower the beams, the lower is the probability that a mobile intersects a beam of the same frequency of a different cell in which the carrier frequency is reused. The extension of the advantage of a narrow beam antenna over an omnidirectional antenna is a function of the beam width of the narrow beam antenna, and the narrower or narrower the beam width, the greater the advantage in terms of performance C / I However, narrow beam antennas have increased in size and complexity compared to omnidirectional antennas and there are major disadvantages in the approach of using a large number of narrow directional antennas in a sectorized approach. • Cellular radio transceivers are dedicated or specialized in particular sectors, which P1093 / 98 MX leads to significant levels of link inefficiency. In practice, this means that many more transceivers are needed in the place of the base station than for an ominidditional cell of the same capacity. • Each sector is treated by the radio-cellular network (ie, the base station controller and the mobile switches) as a separate cell. This means that as a mobile moves between sectors, considerable interaction between the base station and the network is required in order to transfer the call between sectors of the same base station. This interaction involves the transfer of signals and processing in the controller and the switch of the base station and represents a high overhead of the network and reduces the capacity. The problem can be illustrated when considering the necessary operations or the distribution or assignment of frequencies in relation to the structure of a base station. Referring to Figure 4 hereof, the conventional radio-cellular system comprises several layers including a mobile switching center (MSC) 400 which provides an interface between the cellular system and other networks, for example, the public telephone network of P1093 / 98 MX switching (PSTN) or integrated services digital network (ISDN) 401. Each mobile switching center 400 controls several base station systems (BSS) 402-404 than in some systems such as for example the Groupe Systéme Mobile (GSM) or PCS 1900 systems are further divided into a base station controller (BSC) 405 which controls several stations of the base transceiver (BTS) 406-408. Each base transceiver station communicates with several mobile stations (MS) 409-411. At the mobile switching center level, other facilities also exist, such as, for example, the operations and maintenance controller (OMS) 412 and the network management controller (NMC) 413. In the conventional radio-cellular system, the calls are assigned or distributed to the transceivers in the baseband of the cellular radio network, either in the controller of the base station if it is available or, in the controller of the mobile station, as shown in Figure 4 of the present. Any change required in the transfer of a call to a different transceiver has to be communicated through the network, possibly as far as the controller of the mobile station and again back. In some cases, the approach of using a large number of narrow or narrow beams to increase the P1093 / 98 MX system capacity encounters additional problems to those identified above. In particular, as described later in this document in the American digital AMPS system, the beams must be spatially fixed and can not be conducted to follow a mobile station. Using a large number of directional beams under these circumstances introduces additional problems of link inefficiency.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the link inefficiency experienced in cellular radio systems using a plurality of narrow directional beams. Another object of the present invention is to increase the capacity in a cell while maintaining an acceptable ratio of carrier to interference. The specific methods and embodiments in accordance with the present invention adopt the approach of making a cell be served by a plurality of directional beams, each capable of operating or operating on a plurality of carrier frequencies, wherein the carrier frequencies can float anywhere through the plurality of beams, to distribute or assign PJ093 / 98 MX at any time any carrier frequency to any beam. In accordance with a first aspect of the present invention, it is provided in a cellular radiocommunications system comprising: a plurality of transceivers, each one operating a transmission signal on a different carrier frequency; and an antenna array capable of operating a plurality of directional beams, a method for distributing or assigning a set of carrier frequencies to the plurality of beams, wherein; any carrier frequency can be assigned to any beam; and a variable number of carrier frequencies can be assigned to a particular beam in accordance with the traffic requirements of the communications. The directional beams may comprise downlink or uplink beams. The downlink beams adequately comprise beams of directional radiation generated by the antenna. The uplink bundles suitably comprise spatial areas of high gain sensitivity to the received signals generated by the transmitting entities such as for example the mobile stations.

P1093 / 98 MX Preferably, the method comprises the steps of: continuously reviewing several carrier frequencies distributed to each beam; and minimize several carrier frequencies spread each beam at any time. Preferably, the method comprises the step of maintaining a grouped set of transceivers in an undistributed state in which the respective carrier frequencies of the grouped set of transceivers are not distributed to any beam. Preferably, a carrier frequency comprises a plurality of communication channels. The plurality of communication channels may comprise timeslots multiplexed by time division. Preferably, the beams are spatially fixed. Preferably, the method comprises the step of a call originating in an area covered by more than one beam, determining an allocation that the beam will use, depending on the traffic load of each of the coverage beams covering said area . In accordance with a second aspect of the invention, there is provided a method for assigning a plurality of carrier frequencies to a plurality of P1093 / 98 MX radiation beams generated by an antenna of a cellular radio system, where each carrier frequency is multiplexed to carry a plurality of communication channels, the method comprises the steps of: for a beam: monitoring several channels for each beam carrier frequency; monitor the demand for communications calls in the beam and when a new communication call is required to be added to the beam, if a vacant channel is available on an existing carrier frequency of the beam, add the communication call to the existing carrier frequency of the beam and if a vacant channel is not available on an existing carrier frequency of the beam, assign a new carrier frequency to the beam. According to a third aspect of the present invention, there is provided a method for reallocating a plurality of carrier frequencies of a beam of an antenna of a radiocell system, wherein each carrier frequency carries a plurality of communication channels, the method comprises the steps of: monitoring the plurality of channels in the beam; and if the beam has more than one predetermined number P1093 / 98 MX of vacant channels, reassign any channels used among the plurality of carrier frequencies of the beam; and removing a carrier frequency from the beam. The reassignment may be limited to reassigning the channels used to other carrier frequencies only when there is a discontinuity in the communications in the degradation of the channel used, from the perspective of the users of the channel. Preferably, each carrier frequency carries several channels and the number predetermined is at least the number of channels carried by the carrier frequency. According to a fourth aspect of the present invention, there is provided an antenna array for a base station comprising: an antenna capable of forming a plurality of directional beams; a plurality of transceivers, each transceiver operates at a different carrier frequency; a switching matrix means operating to switch any transceiver to any beam; a monitoring means for monitoring various carrier frequencies assigned to the beam; and a control means that operates to determine the P1093 / 98 MX assign the carrier frequencies to the beams and to control the commutation matrix to switch the transceivers to the beams in accordance with the above. Preferably, the monitoring means operates to monitor the use of the carrier frequencies corresponding to each beam and, the control means responds to the monitoring means to control the switching of the communications calls between the carrier frequencies during the calls. Preferably, the monitoring means operates to monitor the use of carrier frequencies corresponding to each beam and the control means responds to the monitoring means to control the commutation of communication calls between different carrier frequencies in the same beam. Preferably, the monitoring means operates to monitor the use of carrier frequencies corresponding to each beam and the control means responds to the monitoring means to control the switching of transceivers between different beams. Preferably, transmission and reception are effected through a common antenna aperture.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention and for P1093 / 98 MX show how it can be put into practice, then only by way of example, modalities, method and specific processes according to the present invention will be described, with reference to the accompanying drawings, in which: Figure 5 illustrates in schematic form an antenna array operating a fixed beam, a fixed transceiver array for assigning carrier frequencies to a plurality of fixed beams; Figure 6 illustrates in schematic form an antenna array that operates a floating transceiver array in which a plurality of transceivers are allowed to float anywhere through a plurality of fixed beams; Figure 7 illustrates a plurality of spatially fixed beams occupying a 120 ° sector of a cell radio cell; Figure 8 illustrates an antenna array in accordance with a specific embodiment of a best form of the invention, wherein a plurality of transceivers can float on either side through a plurality of spatially fixed beams in a cellular radio system; ** -, _. £ JJ. Figure 9 illustrates a plurality of spatially fixed beams occupying a sector of 120 ° of an area P1093 / 98 MX cellular radio cellular; Figure 10 illustrates in general terms a method of assigning frequencies in accordance with the best form of the present; Figure 11 schematically illustrates a data arrangement preserved by a specific mode antenna array in accordance with a best form of the present; Figure 12 illustrates a specific example of a frequency assignment method in accordance with a specific example method of the best form hereof; Figure 13 schematically illustrates a specific example of a frequency modification method in accordance with a best form of the invention herein; Figures 14, 15 and 16 schematically illustrate t-a specific example of operation of a frequency modification process in accordance with a best form described herein.

DETAILED DESCRIPTION OF THE BEST WAY TO REALIZE THE INVENTION Next, the best way contemplated by the inventors to carry out the invention will be described by way of example. In the following description, they are exposed P1093 / 98 MX numerous specific details in order to provide a complete understanding of the invention. However, it will be apparent to one skilled in the art that the present invention can be practiced without using these specific details. In other cases, well-known methods and structures have not been described in detail so as not to obscure the present invention unnecessarily. Specific examples in accordance with the present invention will be described as a possible solution to the restrictions of reuse of frequency in downlink paths in the known North American D-AMPS cellular radio system operating in accordance with IS-54 and IS136. However, the methods disclosed herein are more broadly applicable to other cellular radio technologies, including Groupe Systéme Mobile (GSM), PCS1900, Code Division Multiple Access (CDMA), and Time Division Multiple Access ( TDMA). The conventional North American digital AMPS cellular radio system comprises an analog mobile standard that has also supplied a Time Division Multiple Access mobile telephony standard (TDMA) digital compatible with the analog mobile standard. He American digital AMPS is also referred to as the international standard (International Standard) IS-54, which is P1093 / 98 MX a dual analog / digital mode standard operating in the 850 MHz band and more recently replaced by the international standard IS-136 dual mode analog / digital mobile standard covering the operation of the 850 band MHz and the 1900 MHz band. The D-AMPS standard includes a downlink restriction that avoids the use of individually directed beams for each mobile subscriber station. The D-AMPS rules dictate that in the downlink, the base station must maintain a constant level of transmission throughout the duration of a frame on any particular bearer channel, each time at least one mobile has been assigned to said bearer. It is not possible to devise a scheme that allows the beams to move dynamically from one mobile direction to another, from one time interval to the next. Thus, a downlink beamformer for the D-AMPS has to use a spatially fixed beam approach, where the mobile station moves from beam to beam as it moves geographically and an optimum beam for communication with a station Mobile is selected at any time by uplink measurements of signal quality. Since the radio standard D-AMPS prohibits the beam direction of a radiation beam in a time interval in time interval bases within P1093 / 98 MX of a digital table, mobile stations that leave an area covered by a spatially fixed beam need to communicate with the base transceiver station by an adjacent neighboring beam. Two options that are available for the treatment of mobile stations that move through a plurality of spatially fixed radiation beams are as follows. First, in a spatially fixed beam, the fixed transceiver configuration as shown schematically in Figure 5 hereof, a plurality of transceivers 500, each operating at a separate carrier frequency and each connected in a permanent with a corresponding respective radiation beam emanating from the antenna array 501, the transceivers will be connected to the antenna array by means of a beamformer 502. Second, in a spatially fixed beam, the switched carrier frequency array as schematically illustrated in Figure 6 hereof, a plurality of transceivers 600 each operating at a corresponding respective carrier frequency, the plurality of carrier frequencies will be selected so that they are not interfere with each other, are connected to a beamformer 600 and an antenna array 601 a P1093 / 98 MX through a switching device 603 that covers a cell sector. The switch 603 is capable of connecting any transceiver with any beam of a plurality of beams formed by the beamformer 601 and the antenna array 602, so that each transceiver can "float" through all the beams. At any time a transceiver can receive in only one beam of a sector. In the switched frequency array, when it is determined that a stronger signal from a mobile station is available in a neighboring beam, then the downlink carrier frequency can be switched through the neighboring beam, instead of transferring the call between the frequencies carriers that will be implemented. The benefit of this for the mobile station is that carrier frequency to carrier frequency transfers are not required, thus avoiding the degradation of call quality. In the best form described herein, a plurality of transceivers are allowed to "float" through a plurality of beams in a sector. A frequency modification process is used to minimize the number of carrier frequencies used by any beam at any given moment of time. The unused transceivers operate each on a different respective carrier frequency and are maintained in P1093 / 98 MX a group of reserve transceivers and, they are deployed according to the demand to any beam that requires additional capacity. By maintaining a reserve pool of available transceivers, each operating at a corresponding respective carrier frequency and allowing any carrier frequency to be connected in any beam, the normal link loss incurred by the fixed allocation and sectorization systems can be mitigated. conventional fixed sets of the prior art. The frequency modification process requires that the number of partially loaded transceivers that have a vacant channel capacity are minimized in order to release transceivers that will be returned to the reserve pool. This requires that mobile stations communicating via partially loaded transceivers are sent to other transceivers operating on other carrier frequencies. There may be a capacity advantage of the switched frequency scheme compared to the fixed-frequency fixed-beam scheme which may be significant, as shown by the following example. There will be an advantage in capacity of the fixed-beam and frequency-switched scheme compared to the fixed-beam and fixed-frequency scheme, which can be P1093 / 98 MX significant, as shown by the following example. Assume a three-sector D-AMPS cellular scheme or sectorized with four beams per sector that operates for example purposes only with sixteen voice traffic transceivers per sector. Ignore the control channels represents 16 x 3 (time intervals) = 48 links per sector. With a fixed frequency architecture, four transceivers would be assigned to each beam. Using the Erlang tables, this corresponds to a traffic capacity of 26.4 Erlang at 2% blocking probability. With a switched frequency architecture, using floating transceivers, the but case of link loss will be 2 x (Nb -1), where N ^ represents the number of beams. For the example under consideration, this represents at least 48 -2 x (4 - 1) = 42 links that will be available to carry the traffic. This corresponds to a traffic capacity of 32.8 Erlang at 2% blocking. In this way, the switching frequency approach provides at least a 24% increase in traffic capacity compared to the use of a fixed frequency assignment. The concession against the advantage in the performance of the switched carrier frequency scheme is the fact that the switched beam array may include a P1093 / 98 MX significant additional complexity in the base transceiver station to compensate the commutation. An example of the operation of the best form of the present is illustrated by the following example. Referring to Figure 7 herein, a plan view of a base transceiver station 700 is illustrated schematically at the center of a cell 701, which in the example radiated seven downlink beams B1-B7 on a sector of 120 ° 702. Each beam is substantially spatially fixed and the beams operate at the carrier frequencies, which are sufficiently separated from each other so as not to cause interference between them or with other beams radiating into adjacent cells. If a mobile station MSI operating at the carrier frequency fx and falling or being inside the radiation beam B7 moves out of an area covered by the beam of radiation B7 and towards an area covered by an adjacent beam of radiation B6 , the communication with the base station is lost through the B7 beam and the base transceiver station must communicate with the mobile by means of a B6 beam. The mobile station can resume communication in one of two ways: • First, if it is necessary for the carrier frequency f t used to support communication while in beam B7. stay in beam B7 P1093 / 98 MX (for example, due to the continuity of communication with other mobiles in the B7 beam and the D-AMPS downlink restriction), then the mobile that enters an area covered by the B6 beam must be transferred to another carrier frequency in beam B6. In this case, the vacant channel on the carrier frequency fi created by the output of the mobile station MS2 and the adjacent beam can be occupied by other cells in the beam B7. It may be possible to re-arrange or re-accommodate calls made on other carrier frequencies underutilized in beam B7 on the carrier frequency fi to obtain a fully vacant carrier frequency in beam B7, which can then be removed from the beam Bl and reassigned somewhere else. Second, if the carrier frequency ±? which supports the mobile in beam B7 becomes vacant when the mobile leaves the area covered by beam B7 (because the mobile station MSI was the only mobile station supported by that carrier frequency), then the carrier frequency fi may be required "from the az B7 and switched to the B6 beam and can continue supporting the mobile MSI in the area covered by the B6 beam and, thus, it is not necessary to transfer the frequency of the mobile MX MSI. While the example in Figure 7 is related to the downlink, the operation of the uplink beam areas of gain sensitivity for communication between the mobile stations and the base transceiver station can be made equivalent, although the number of uplink beams that are emitted from the base transceiver station 700 can be different from the number of downlink radiation beams that are emitted from the same base transceiver station. Referring now to Figure 8 herein, a specific embodiment of an antenna array according to the present invention is shown schematically for a base transceiver station of a cellular radio system, the antenna array is capable of implementing a method of specific frequency assignment in accordance with the present invention. The antenna array shown may be suitable for a single sector of a three-sector or trisectorized cell, however, it will be appreciated that the architecture shown is applicable to adaptation to service or serve a plurality of sectors of a cell. The antenna array comprises a plurality of transceivers from Txi to Txn, 800, each capable of emitting a digital communications signal P1093 / 98 multiplexed MX that supports a plurality of corresponding respective communication channels, each transceiver operates at a corresponding respective carrier frequency; a transceiver switch and a combiner matrix 801 switches a plurality of carrier frequency signals of the respective transceivers 800 to a plurality of power amplifiers 802; a plurality of sources Ci to Cm of the communication channel signal, the signal sources of the channel will be input to a time division multiplexer and channel switching device 803, which is capable of switching any channel signal to any transceiver in such a way that a plurality of the channel signals can be multiplexed on any carrier frequency in any combination; a monitor means 804 for monitoring various carrier frequencies assigned to each beam and, for monitoring various communication channels assigned to each carrier frequency and, irrespective of whether those communication channels are vacant or occupied by communications signals; and, a control means 805 that operates to control the frequency switch and the combiner matrix 801 to switch the transceivers to the beams and to control the assignment of carrier sequences to the beams, in accordance therewith, the control means will respond to the P1093 / 98 MX monitoring means to control the switching of communications calls between carrier frequencies during communications calls by operating the channel switch and multiplexer device 803 to effect the switching of the sources Cl-Cm of the signal of the communication channel to individual transceivers of the plurality of transceivers TX? -TXn, a multi-element antenna array 806 for transmitting and receiving a plurality of spatially fixed directional beams; a beamforming matrix 807 for forming a plurality of beams in the multiple element antenna array 806; and a plurality of duplexers 808 located between the beamforming matrix 807 and the antenna array 806 for separating the uplink and downlink communication signals. Each transceiver TX? ~ TXn operates at a different respective carrier frequency and carries a plurality of communication channels, for example, in the form of timeslot multiple access time intervals. A carrier frequency can be assigned to any one beam of a plurality of beams formed by the antenna array 806 and the beamforming matrix 807, the corresponding transceiver will be switched to the selected and appropriate beam by the commutator and matrix P1093 / 98 combinator MX 801, under the control of the control unit 805. The communication of the channel switch and the multiplexer device 803 receives the signals of the communications channel coming from each of the sources C? -Cm of the signal of the communication channel and the transceiver switch and the combiner matrix 801 that receive the signals from each of the transceivers TX ± -TXn allows any communications channel to be placed on any transceiver and the output of any transceiver to be placed in any one beam. In this way, the channels can be reassigned between the transceivers, i.e., reassigned between the carrier frequencies and the carrier frequencies can be reassigned between the beams. While the embodiment of Figure 8 illustrates a downlink beamforming array, the principles and methods described herein are equally applicable to an uplink beamformer array, wherein instead of a beam being formed of radiation as in the case of downlink, in the case of uplink, the beam comprises a zone of gain sensitivity from which "the signals received by a mobile station are accepted." Referring in the present to Figure 9, schematically illustrates a plan view of a sector P1093 / 98 MX of 120 ° of a cell occupied by four spatially fixed downlink radiation beams, each having an angular beam width of about 30 ° in a contour of -4dB. The four radiation beams are an example of beams formed by the antenna array of Figure 8 comprising eight antenna elements or, depending on the way the beamforming matrix 807 is configured, the eight element antenna array it can form a different number of beams, for example, seven beams that cover the sector of 120 °. Each beam comprises several different carrier frequencies, the number will be variable for each beam and, will be controllable by the control unit 805, which controls the transceiver switch and the combiner matrix 801 to assign different transceivers to the different beams in accordance with the demand of communications calls from mobile stations that fall or are within the sector. For example, when mobile stations are allocated relatively uniformly across the sector, the number of carrier frequencies assigned to each beam will be the same or similar beam-to-beam. Without . However, when a concentration of mobile stations is present in an area covered by a particular beam, more carrier frequencies may be assigned to said beam in order to meet the demand P1093 / 98 MX capacity of mobile stations. When a critical point is present in the capacity and within an area covered by a single beam there are a large number of mobile stations, the number of carrier frequencies comprising the beam can be increased to a level such that there are sufficient time intervals for support communications with all mobile stations in the beam. The number of mobile stations within a radiation beam is determined from the number of uplink signals corresponding to the number of mobile stations. The data related to the number of mobile stations are input to the monitor and control units 804, 805 that operate a frequency assignment algorithm to assign the frequencies to the spatially fixed beams as shown. The operation of a specific method in accordance with the present invention will be described below. When a mobile station enters an area covered by a beam, the base transceiver station receives a call from the mobile. The monitor unit 804 and the control unit 805 operate algorithms to maintain the data describing the number of mobile stations within a sector served by the antenna array. The data P1093 / 98 MX are arranged as follows: • data describing a grouped set of available carrier frequencies (each corresponding to a respective transceiver) that can be assigned to beams covering a sector without interfering with adjacent sectors or with adjacent cells within of interference rules? predetermined; • data describing the ordinary carrier frequencies assigned to the beams (and to the respective transceivers) and the ordinary mobile stations assigned to said carrier frequencies. Referring to Figure 10 hereof, a process operated by the monitoring unit and by the control unit to monitor the carrier frequencies assigned to the beams, the occupation of those carrier frequencies by the communications signals and the switching of carrier frequencies and channels to the beams. In the best form of the present, the process is implemented as an algorithm performed by a processor comprising the monitor unit 804 and the control unit 805. In step 1000, a grouping of allowable carrier frequencies that are found is maintained. available to be used in the beams. These are carrier frequencies that are not currently P1093 / 98 MX assigned to no radiation beam and are kept in reserve in order to be assigned to the beams to meet the demand of users of mobile stations. In step 1001, the monitoring unit 804 monitors the communications calls in each antenna beam and maintains the data related to the number of carrier frequencies in each beam and the occupancy of the communication channels comprising those carrier frequencies. Depending on the number of incoming calls monitored in the uplink, in step 1002, individual bearer frequencies are assigned to each beam in the uplink and downlink beams that have zones corresponding to those of the mobile station calling for calls from communications. The carrier frequencies that are selected for allocation to the beams can be selected from the cluster on random bases. The reason for this is that when a plurality of base stations are operating, if all the base stations were to select frequencies carrying the spectrum of available frequencies in a predetermined manner, certain frequencies would be selected in preference to other frequencies and, the probability of blocking between different sectors or different base stations can be increased due to a bias towards the selection of certain frequencies. By ensuring that the P1093 / 98 MX selection of the carrier frequencies of the cluster is performed on random bases, the probability of interference with other sectors and with other base stations can be randomized, resulting in a reduced carrier-to-interference ratio. Additionally, this helps to randomize the interference of co-channel cells. In step 1003, the monitoring means 804 monitors the use of channels of the carrier frequencies in each beam. In step 1004, communications calls that are occupying underutilized carrier frequencies in a beam, i.e., carrier frequencies having several communication channels or vacant time slots, are reassigned to other frequencies in the same beam. If any beams have more than a predetermined number of vacant channels, taking all their carrier frequencies in ditch and there are enough vacant channels to understand several channels carried by a single carrier frequency, then potentially, by rearranging the communication channels on other carrier frequencies. that beam, can a carrier frequency be released for reassignment to another beam e? step 1005. The monitoring and control units operate in the process of "frequency modification" as described below to minimize the number of P1093 / 98 MX carrier frequencies assigned to any beam, consistent with the capacity demanded by the user in a space area covered by said beam. In step 1005, any carrier frequencies released by the frequency modification process are reassigned to the pooled set of unused carrier frequencies. This is done by the monitoring unit and the control unit that controls the switch and the combiner matrix 801 to disconnect an available transceiver, released as part of the frequency modification process, by disconnecting them from their beam. It can be restricted to the frequency modification process so that it operates on a carrier only during discontinuities in the transfer of communication data, for example, during discontinuities or natural pauses when speaking, so that any degradation due to transfer can be better tolerated . A plurality of individual communication channels as a carrier frequency can monitor the activity of communication data and, when the communication data is not being transmitted, the frequency modification process can be activated. In Figure 11 hereof, an example of data preserved by the monitor unit 804 and PÍO93 / 98 MX the control unit 805. This example related to a multiplexer system by division of time, in which each transceiver operating in a corresponding carrier frequency transports a plurality of multiplexed channels by time division. The preserved data includes a list of each of the beams of B1-B7 and their corresponding frequencies that normally comprise said beams and, the corresponding communication channels, each one corresponding to a respective transceiver carried by the carrier frequencies. For example, in Figure 11, the beam Bl comprises the carrier frequencies fi, f, fi2, f20 3l- The carrier frequency fi carries the channels Ci, C2, C3, each of the three pairs of time slots in the transmission of the TDMA-3 system will be occupied. On the other hand, the carrier frequency f2o carries the channels C12, C21 in two of the time interval pairs and a third time interval in the box that is vacant (indicated by B). Similarly, carrier frequency F31 carries a C30 channel, and has two pairs of vacant time slots within a frame. Next, an operation of the antenna array will be described upon receiving a call capacity request by a new mobile station in an area covered by a beam, for example, beam B3. Referring to Figure 12 P1093 / 98 MX of the present, in step 1201, the monitor unit 1004 and the control unit 805 add the new call from the new mobile to the list of calls transported in the beam B3 and, in step 1202, verify all carrier frequencies in beam B3 to determine if there is a carrier frequency having a vacant time slot that can carry the call to the new mobile station in the area covered by beam B3. If there is a vacant time slot, as is the case in the data described in Figure 11, in step 1203, a channel source supporting the call to the mobile station is switched to a carrier frequency having a time slot. vacant, for example, the carrier frequency I20 / ° Iue? G forms in the radiation beam B3 by means of the combiner matrix 801, the power amplifier 802, the beamforming matrix 807 and the antenna array 806. In the step 1204, the call is transmitted over a time slot available on the carrier frequency in beam B3. However, in the case where there is no vacant time slot available at any of the carrier frequencies comprising beam B3, at step 1205, a new carrier frequency of the carrier frequency reservation pool is selected. The new carrier frequency is selected so that it is not P1093 / 98 MX interferes with other carrier frequencies that radiate in adjacent sectors. In case 1206, the call to the new mobile transceiver connected by the channel switch and the time division multiplexer 803 to the corresponding frequency transceiver source of the new carrier frequency. In step 1207, the new carrier frequency that supports the call in one of its time slots, switches over the beam B3 and, in step 1208, the call is transmitted in a time slot of the new carrier frequency in the beam B3. Thus, in the best form of the present, as mobile stations are added to a beam, the number of carrier frequencies comprising the beam is increased to compensate for the required increase in capacity to support communications with the increase in the number of carriers. the mobile stations. For a call that originates in the area covered by more than one beam in the uplink or in the downlink, the control algorithm operated by the control unit determines which beam to use, after considering the traffic load of each beam in the zone. The monitor unit 804 and the control unit 805 operate an algorithm to add new carrier frequencies to a particular beam that is experiencing high capacity demand. However, as the mobile stations finish theirP1093 / 98 MX calls or move out of the beam, the time slots on the carrier frequencies previously assigned to a specific beam become vacant and are released for use. The monitor unit 804 and the control unit 805 operate a frequency modification algorithm that implements a frequency modification process to optimize the assignment of calls to the carrier frequencies and to optimize the number of carrier frequencies comprising each beam. Referring to Figure 13 hereof, a general view of a process to monitor each beam in a sector continuously and to modify the underutilized carrier frequencies is shown schematically. In step 1300, all carrier frequencies in a single beam are monitored continuously. In step 1301, if a beam has a predetermined number of vacant channels in any combination of the carrier frequencies comprising that beam, in step 1302, the calls occupying the carrier frequencies having vacant channels are transferred to other carrier frequencies in that beam that has vacant channels if these are available. The object is to concentrate the communications calls in the channels in the minimum number of carrier frequencies per beam, thus allowing a frequency to appear P1093 / 98 Vacant carrier MX, which can be removed or removed from the beam in step 1303 and returned to the reserve pool of carrier frequencies available for deployment on any of the beams to deal with future capacity demands. In step 1301, if a predetermined number of vacant channels do not appear in the beam, then it appears that the beam will be configured in optical form with respect to the number of carrier frequencies assigned to the beam and, the algorithm continues to monitor the 10 beam in step 1300. Each beam of the sector is monitored continuously in order to optimize the number of carrier frequencies in the beam and, to use the channels of the carrier frequencies that comprise the beams to obtain the highest possible occupancy of channels by the 15 calls. In the following, a specific example of a frequency modification operation according to the best form hereof will be described in more detail. 20 Referring to Figure 14 hereof, an example of a modification process to minimize the number of carrier frequencies is illustrated.

Not used by each beam in a sector. If, for example, five mobile stations MS1-MS5 were present in a 25 area covered by beam B3, as shown in Figure P1093 / 98 MX 14, the five mobile stations can be supported by three carrier frequencies fi, fß, shown in Figure 14 here, where the time division multiple access multiplexing (TDMA-3) regime is operating. of three time intervals. Each carrier frequency is divided into several time frames, each time frame comprising three time intervals. Each time slot in a frame comprises a separate communication channel for communicating with a separate mobile station. In the example of Figure 14, the five mobile stations MS1-MS5 are supported in five of the nine time slots provided by the three carriers f? ~ F3. Each of the carrier frequencies fl Y 3 has an unoccupied channel, that is, an unoccupied time interval in each frame. The second carrier frequency f2 has two unoccupied time slots, corresponding to the two unoccupied channels. The monitoring means monitors the number of carrier frequencies that occupy beam B3 and finds the three carrier frequencies f? ~ F3. The monitoring means also monitors the number of time slots per frame occupied by calls, for each carrier frequency of beam B3 and, determines, in the case of Figure 14, that two time slots per frame are occupied by calls carried by the carrier frequency fi y, P1093 / 98 MX similarly for the carrier sequence Í3, two time slots per frame are occupied by calls to the mobiles MS3, MS5. However, for the carrier frequency f2, only one time interval per frame is occupied by one call, in this case, the mobile station MS2 leaving two free time slots not occupied by frame on the carrier f2 • The monitoring means reassigns the call to the mobile station MS2 within the geographical area covered by the beam B3 to another carrier frequency comprising the beam B3. Two options are possible. The call to the mobile station MS2 can be moved to a vacant time slot in the carrier sequence fi, or to a vacant time slot on the carrier frequency f3. The two options are shown in Figures 15 and 16, respectively. The monitoring means operates the algorithm and, the control unit generates signals that redirect or redirect the call to the mobile station MS2 from the underutilized carrier frequency I2, towards a vacant time slot on any of the carrier frequencies fl or f3. The monitoring means maintains a table, in the form of an electronic database, which contains information concerning the allocation of calls / time intervals to the carrier frequencies.

P1093 / 98 MX The modification algorithm continuously inspects the time / frequency slot allocation table for underutilized carrier frequencies and if a time slot occupying an underutilized carrier frequency in the beam can be moved to another carrier frequency in the same beam, the modification algorithm generates modification data, in the form of modification signals, instructing the reassignment of a time interval to another carrier frequency in the same beam. In the case of TDMA-3, the modification algorithm seeks to ensure that there are no more than two free time slots on any carrier frequency assigned to a beam. If a carrier frequency has more than two free time slots, it is assigned to a particular beam, that is, an underutilized carrier frequency, then the frequency assignment algorithm reassigns the underutilized carrier frequency to the carrier frequency reservation pool. After the reassignment of a call to a vacant time slot on a carrier frequency of the same beam B3, it leaves empty the previously used carrier frequency Í2, that is, does not transport communications to the mobile stations. The frequency assignment algorithm operated by the monitoring means operates to return the carrier frequency f2 not P1093 / 98 MX used to the reserve pool of carrier frequencies, resulting in a beam B3 comprising only two carrier frequencies fi, f3 that carry calls to the five mobiles MS1-MS5. Although a specific embodiment and a method in the best form of the present make use of time division multiplexed channels, the methods according to the present invention are not restricted to the use of time division multiplexed channels, but are only restricted by the particularities of the present claims. Similarly, while the best form described herein has a detailed description with respect to a downlink radiation beam, the methods according to the present invention as claimed in the claims herein encompass uplink beams.

P1093 / 98 MX

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. In a cellular radio system comprising: a plurality of transceivers that operate, each, a transmission signal on a different carrier frequency; and an antenna array capable of operating a plurality of directional beams, a method for assigning a set of carrier frequencies to the plurality of beams, wherein: any carrier frequency can be assigned to any beam; and a variable number of said carrier frequencies can be assigned to a particular beam in accordance with the requirements of communication traffic. 2. A method according to claim 1, comprising the steps of: continuously reviewing several carrier frequencies assigned to each beam; and minimize the number of frequencies P1093 / 98 MX carriers assigned to each beam at any time. A method according to claim 1 or 2, comprising the step of: maintaining a grouped set of transceivers in an unassigned state in which the respective carrier frequencies of the grouped set of transceivers are not assigned to any beam. 4. A method according to any of the preceding claims, wherein a carrier frequency comprises a plurality of communication channels. 5. A method according to claim 4, wherein the plurality of communication channels comprises timeslots multiplexed by time division. 6. A method according to any of the preceding claims, wherein the beams are spatially fixed. A method according to any of the preceding claims, comprising the step of: for a call originating in an area covered by more than one beam, determining an assignment of which beam to use, depending on the traffic load of each beam of coverage that covers this area. 8. A method for assigning a plurality of carrier frequencies in a plurality of beams of P1093 / 98 MX radiation generated by an antenna of a radiocell system, where each carrier frequency is multiplexed to transport a plurality of communication channels, the method comprises the steps of: for a beam: monitoring several channels for each carrier frequency of the make; monitor the demand for communications calls in the beam and when a new communication call is required to be added to the beam; if a vacant channel is available on an existing carrier frequency of the beam, add the communication call to the existing carrier frequency of the beam and ".- if a vacant channel is not available on an existing carrier frequency of the beam, assign a new carrier frequency to the beam 9. A method for reallocating a plurality of carrier frequencies of a beam of an antenna of a cellular radio system, wherein each carrier frequency carries a plurality of communication channels, the method comprising the steps of: monitoring the plurality of channels in the beam, and if the beam has more than a predetermined number of vacant channels, reassign any channels P1093 / 98 MX used among the plurality of beam carrier frequencies; and removing or removing the beam carrier frequency. A method according to claim 9, wherein the step of reassigning the channels used is restricted to occur during communication discontinuities in the channels used. A method according to claim 10, wherein each carrier frequency carries several channels and the predetermined number is at least the number of channels carried by a carrier frequency. 12. A base station antenna array comprising: an antenna capable of forming a plurality of directional beams; a plurality of transceivers, each transceiver operates at a different carrier frequency; a switching matrix means operating to switch any transceiver to any beam; a monitoring means for monitoring various carrier frequencies assigned to a beam; and a control means that operates to determine the assignment of the carrier frequencies to the beams and to control the commutation matrix to switch the PX093 / 98 MX transceivers to the beams in accordance with this. An arrangement according to claim 12, wherein: the monitoring means operates to monitor the use of carrier frequencies corresponding to each beam and the control means responds to the monitoring means to control the switching of communication calls between the frequencies carriers during calls. 14. An antenna array according to claim 12 or 13, wherein the monitoring means operates to moni- tor the use of carrier frequencies corresponding to each beam; and the control means responds to the monitoring means to control the switching of communications calls between different carrier frequencies on the same beam. 15. A method according to any of claims 12, 13 or 14, wherein: the monitoring means operates to monitor the use of carrier frequencies corresponding to each beam; the control means responds to the monitoring means to control the switching of transceivers P1093 / 98 MX between different beams. 16. An arrangement according to claim 12, wherein the transmission and reception are effected through a common antenna aperture. P1093 / 98 MX SUMMARY OF THE INVENTION A frequency assignment method for assigning carrier frequencies in a plurality of fixed beams in a radio-cellular base transceiver station comprising maintaining a reserve pool of carrier frequencies (1000), such that any frequency The available carrier can be assigned to any fixed beam at any time, in order to deal with the capacity demands of the mobile stations within an area covered by a fixed beam. A frequency assignment algorithm operates, for example, to allow a plurality of transceivers to float anywhere through a plurality of fixed directional beams. More carrier frequencies can be added to a beam to cope with the increase in demand for the capacity of the mobile station. The occupation of channels in the carrier frequencies is continuously monitored (1001) and the number of carrier frequencies per beam is continuously monitored in order to release the unused carrier frequencies towards a reserve pool of carrier frequencies (1004) , allowing the redeployment of unused carrier frequencies to other beams, when necessary. The carrier frequencies are "periodically modified" (1005) by evaluating the number of vacant channels in the carrier and, PÍO93 / 98 MX reassigning any vacant unused channels to other carrier frequencies. The modification process can be restricted so that it operates during the natural discontinuities of speech, to avoid the degradation of the channel. P1093 / 98 MX